A method for fast neutron time-of-flight spectrum calibration

Abstract

The present application discloses a method for calibrating a fast neutron time-of-flight spectrum, comprising: obtaining a logic signal of a photoelectric system and at least two delayed logic signals corresponding to the logic signal of the photoelectric system, wherein the at least two delayed logic signals are signals obtained by delaying the logic signal of the photoelectric system; determining the time difference between the logic signal of the photoelectric system and each delayed logic signal using an oscilloscope; when each time difference is included in a preset reference delay time set, calibrating a time-amplitude converter and a multi-channel analyzer used for fast neutron time-of-flight spectrum measurement using each time difference to obtain a time pulse amplitude spectrum corresponding to each time difference, and obtaining a channel address value corresponding to each time difference from each time pulse amplitude spectrum; performing data fitting on each time difference and the channel address value corresponding to each time difference to obtain a relationship between time and channel address, thereby completing the time calibration of the fast neutron time-of-flight spectrum.

Description

Technical Field

[0001] The present application relates to the technical field of fast neutron energy spectra, and is related to, but not limited to, a fast neutron time-of-flight spectrum calibration method. Background Art

[0002] In related technologies, a fast neutron detector is used to measure fast neutrons to obtain an electrical signal. This electrical signal is then split into two paths through a constant ratio timer. One path is directly connected to the start interface of a time-amplitude converter (TAC), and the other path is connected to the stop interface of the TAC after passing through a delay.

[0003] However, in practice, the delay time indicated on the delay device is not always accurate. For example, over time or due to improper use, time drift can occur. This can lead to inconsistencies between the actual delay time of the two signals and the delay time set on the delay device. This makes it impossible to accurately determine the correspondence between the delay time and the channel address, which in turn affects the measurement of neutron energy. Furthermore, related technologies use neutron detectors as signal sources, requiring the neutron source to excite the neutron detector to generate an electrical signal. This can expose personnel to radiation hazards. Summary of the Invention

[0004] In view of this, an embodiment of the present application provides a fast neutron time-of-flight spectrum calibration method.

[0005] The technical solution of the embodiment of the present application is implemented as follows:

[0006] The present invention provides a method for fast neutron time-of-flight spectrum calibration, the method comprising:

[0007] Acquire a logic signal of the optoelectronic system and at least two delayed logic signals corresponding to the logic signal of the optoelectronic system, wherein the at least two delayed logic signals are signals obtained by delaying the logic signal of the optoelectronic system;

[0008] Determining the time difference between the logic signal of the optoelectronic system and each delayed logic signal using an oscilloscope;

[0009] When each time difference is included in a preset reference delay time set, the time-to-amplitude converter and the multi-channel analyzer used for fast neutron time-of-flight spectrum measurement are calibrated using the time differences to obtain a time pulse amplitude spectrum corresponding to each time difference, and the channel address value corresponding to each time difference is obtained from each time pulse amplitude spectrum;

[0010] Data fitting is performed on the time differences and the channel address values ​​corresponding to the time differences to obtain the relationship between time and channel address, so as to complete the time scale of the fast neutron time-of-flight spectrum.

[0011] The present invention provides a method for calibrating a fast neutron time-of-flight spectrum. The method comprises: first obtaining a logic signal of an optoelectronic system and at least two delayed logic signals corresponding to the logic signal of the optoelectronic system, wherein the at least two delayed logic signals are signals obtained by delaying the logic signal of the optoelectronic system; then, using the waveform displayed on an oscilloscope to determine the time difference between the logic signal of the optoelectronic system and each delayed logic signal; then, when each time difference is included in a preset reference delay time set, calibrating a time-amplitude converter and a multi-channel analyzer used for fast neutron time-of-flight spectrum measurement using each time difference to obtain a time pulse amplitude spectrum corresponding to each time difference, and obtaining a channel address value corresponding to each time difference from each time pulse amplitude spectrum; finally, performing data fitting on each time difference and the channel address value corresponding to each time difference to obtain a relationship between time and channel address, thereby completing the time calibration of the fast neutron time-of-flight spectrum. In this way, on the one hand, the signal source uses a luminous body, and there is no need for fast neutrons to excite a fast neutron detector to generate an electrical signal, thereby preventing radiation damage to personnel. On the other hand, the oscilloscope can accurately determine the time difference between the logic signal of the optoelectronic system and each delayed logic signal, that is, ensure the accuracy of the time difference between the logic signal of the optoelectronic system and each delayed logic signal. Based on this precise time difference, the precise relationship between time and channel address can be determined, that is, the time scale of the fast neutron flight time spectrum can be accurately completed, thereby improving the effectiveness and accuracy of fast neutron energy measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is an electronic block diagram for obtaining a pulse amplitude spectrum for calibrating a fast neutron time-of-flight spectrum in the related art;

[0013] Figure 2 A schematic diagram of an implementation flow of the fast neutron time-of-flight spectrum calibration method provided in an embodiment of the present application;

[0014] Figure 3 A schematic diagram of an implementation flow of a method for obtaining a logic signal and at least two delayed logic signals of an optoelectronic system provided in an embodiment of the present application;

[0015] Figure 4 A schematic diagram of the structure of a photoelectric conversion circuit provided in an embodiment of the present application;

[0016] Figure 5 A schematic diagram showing the logic signals of the optoelectronic system provided in an embodiment of the present application;

[0017] Figure 6An electronic block diagram for obtaining a pulse amplitude spectrum of a calibrated fast neutron time-of-flight spectrum provided in an embodiment of the present application;

[0018] Figure 7 A schematic diagram showing the relationship between the waveforms of two signals when the signal delay is 0 ns provided in an embodiment of the present application;

[0019] Figure 8 A schematic diagram showing the relationship between the waveforms of two signals when the signal delay is 150ns provided in an embodiment of the present application;

[0020] Figure 9 A schematic diagram showing a time pulse amplitude spectrum when a signal is delayed by 150 ns according to an embodiment of the present application;

[0021] Figure 10 A schematic diagram showing the relationship between the waveforms of two signals when the signal delay is 300ns provided in an embodiment of the present application;

[0022] Figure 11 A schematic diagram showing a time pulse amplitude spectrum when a signal is delayed by 300 ns according to an embodiment of the present application;

[0023] Figure 12 A schematic diagram showing the relationship between the waveforms of two signals when the signal delay is 450ns provided in an embodiment of the present application;

[0024] Figure 13 A schematic diagram showing a time pulse amplitude spectrum when a signal is delayed by 450ns according to an embodiment of the present application;

[0025] Figure 14 A schematic diagram showing the relationship between the waveforms of two signals when the signal delay is 600ns provided in an embodiment of the present application;

[0026] Figure 15 A schematic diagram showing a time pulse amplitude spectrum of a signal with a 600ns delay provided by an embodiment of the present application;

[0027] Figure 16 A schematic diagram showing the relationship between the waveforms of two signals when the signal delay is 750ns provided in an embodiment of the present application;

[0028] Figure 17 A schematic diagram showing a temporal pulse amplitude spectrum when a signal is delayed by 750 ns according to an embodiment of the present application;

[0029] Figure 18 A schematic diagram showing the relationship between the waveforms of two signals when the signal delay is 900ns provided in an embodiment of the present application;

[0030] Figure 19A schematic diagram showing a time pulse amplitude spectrum of a signal with a 900ns delay provided by an embodiment of the present application;

[0031] Figure 20 A schematic diagram showing the effect of the data fitting results provided in the embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limiting this application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0033] In the following description, reference is made to “some embodiments”, which describes a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0034] In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0036] In order to better understand the fast neutron time-of-flight spectrum calibration method provided in the embodiments of the present application, the neutron time-of-flight spectrum calibration method in the related art and its existing shortcomings are first described.

[0037] Neutron spectrum measurement is a fundamental research area in neutron physics and a key component of neutron detection. It has made significant contributions to the development of nuclear physics and serves as a crucial tool for studying physical mechanisms in other fields, thus possessing significant significance. Studying the energy spectrum of neutrons produced by nuclear reactions can provide information on nuclear energy levels, while measuring the energy spectrum of inelastic neutrons directly provides information on nuclear excitation energy levels. Measuring the fission neutron spectrum of fissile elements and the neutron spectrum in various power plants is essential for reactor design and testing. For example, measuring the neutron spectrum outside the blanket of a giant fission-fission hybrid reactor can provide characteristic quantities of the hybrid blanket. Measuring the neutron spectrum around a reactor can verify its protection level. Furthermore, precise neutron spectrum measurement provides a crucial technical foundation for advancements in space exploration, plasma diagnostics, radiotherapy, and radiation protection.

[0038] Among them, the neutron flight time method is the most common method for measuring neutron energy spectrum and has the best neutron energy resolution. Its basic principle is to obtain neutron energy by measuring the time it takes for neutrons to fly a certain distance within the non-relativistic speed range. The relationship between neutron flight time and energy can be expressed as the following formula (1):

[0039]

[0040] In the above formula (1), t represents the flight time of the neutron, which can be a thermal neutron or a fast neutron, and the unit is second (s); l represents the flight distance of the neutron, and the unit is meter (m). For example, the flight distance can be 10m; E n Indicates the kinetic energy of the neutron, that is, the energy of the neutron, the unit is Joule (J); m n represents the mass of a neutron. For example, the mass of a neutron may be 1.67E-27 kilograms (kg).

[0041] In the related art, the electronic diagram of neutron flight time measurement is as follows Figure 1As shown, the electronic schematic includes a TAC 101, a multi-channel analyzer (MCA) 102, and a data acquisition system 103. The TAC 101 receives two signals, namely a neutron take-off signal and a neutron stop signal. The TAC 101 converts the time difference (or time interval) between the two signals into a voltage amplitude, thereby representing the time difference between the two signals through the voltage amplitude. The MCA 102 receives the voltage amplitude output by the TAC 101 and converts the voltage amplitude into a channel address value. The data acquisition system 103 is used to perform statistics on the channel address values ​​obtained by the MCA 102. Typically, the data acquisition system 103 and the MCA 102 can be combined to map signals of different voltage amplitudes to different channel address values, with signals with larger voltage amplitudes corresponding to larger channel address values.

[0042] In actual measurement, the pulse amplitude spectrum of the flight time is obtained, so it is necessary to time-scale the corresponding TAC and MCA to obtain the relationship between the neutron flight time and the channel address.

[0043] For neutrons with energies greater than 1 kiloelectron volt (keV), the relationship between neutron energy and flight time when the flight distance is 10m is shown in Table 1:

[0044] Table 1 Relationship between neutron energy and flight time when the flight distance is 10m

[0045]

[0046] As can be seen from Table 1, for neutrons with energies ranging from 1 keV to 1 giga-electron-volt (GeV) at a distance of 10 m, the neutron flight time ranges from 22.8 nanoseconds (ns) to 22.8 microseconds (μm), spanning three orders of magnitude.

[0047] For a given application, the range of neutron time-of-flight (TOF) is generally small, requiring only the selection of appropriate delay electronics. For example, for neutron TOF scales above 100 MeV, the Ortec 425A (with a time delay range of 2 ns to 65 ns) is suitable; for keV neutron TOF scales, the Ortec 416A (with a time delay range of 0.1 μs to 110 μs) is suitable; and for MeV neutron TOF scales, the Ortec GG8020 (with a time delay range of 70 ns to 1000 ns or 0.4 μs to 10 μs) is suitable.

[0048] In related technologies, the technical solution adopted for neutron time-of-flight spectrum calibration is to divide the detector output signal used to measure the neutron time-of-flight into two paths after passing through a timer. One path is directly connected to the Start interface of the TAC, and the other path is connected to the Stop interface of the TAC after passing through a delay device.

[0049] However, the delay time marked on the delayer is not necessarily accurate. For example, if it is used for a long time or improperly, there will be time drift. This will cause the actual time difference between the two signals to be inconsistent with the delay time set on the delayer, making it impossible to obtain an accurate correspondence between time and channel address, which in turn affects the measurement of neutron energy.

[0050] Based on the problems existing in the related art, the embodiment of the present application provides a fast neutron flight time spectrum calibration method. Figure 2 An implementation process of the fast neutron time-of-flight spectrum calibration method provided in the embodiment of the present application is as follows: Figure 2 As shown, the fast neutron time-of-flight spectrum calibration method includes:

[0051] Step S201 : acquiring a logic signal of the optoelectronic system and at least two delayed logic signals corresponding to the logic signal of the optoelectronic system.

[0052] Here, the at least two delayed logic signals are signals obtained by delaying the logic signal of the optoelectronic system. In actual implementation, the delay processing of the logic signal of the optoelectronic system can be implemented using a delay electronics plug-in. Multiple delay times can also be set using the delay electronics plug-in, thereby obtaining multiple delayed logic signals. The number of delayed logic signals can be a custom setting value.

[0053] In actual implementation, the number of delayed logic signals is equal to the number of delay times set by the electronics plug-in. Since two points can define a straight line, the number of delayed logic signals is greater than or equal to 2. In other words, the number of delay times is greater than or equal to 2. For example, assuming the number of delay times is 6, the delay times can be 150ns, 300ns, 450ns, 600ns, 750ns, and 900ns.

[0054] In some embodiments, the delay electronics package may be a GG8020.

[0055] Step S202: using an oscilloscope to determine the time difference between the logic signal of the optoelectronic system and each delayed logic signal.

[0056] Here, the logic signal of the optoelectronic system and each delayed logic signal are input into an oscilloscope respectively, so as to use the oscilloscope to display the logic signal of the optoelectronic system and each delayed logic signal respectively, and read their time difference. The time difference displayed by the oscilloscope is the actual time difference between the two signals.

[0057] Step S203: When each time difference is included in a preset reference delay time set, the time-to-amplitude converter and the multi-channel analyzer used for fast neutron time-of-flight spectrum measurement are calibrated using each time difference to obtain a time pulse amplitude spectrum corresponding to each time difference, and the channel address value corresponding to each time difference is obtained from each time pulse amplitude spectrum.

[0058] Here, the preset reference delay time set includes at least two reference delay times. Each reference delay time in the preset reference delay time set matches the actual flight time of fast neutrons. The number of reference delay times in the preset reference delay time set can be a custom setting value. Since two points can determine a straight line, based on this, the number of reference delay times in the preset reference delay time set is greater than or equal to 2.

[0059] In actual implementation, the preset reference time set is the set of delay times set by the above-mentioned delay electronics plug-in.

[0060] In the embodiment of the present application, a determination is made as to whether each time difference displayed by the oscilloscope is included in a preset reference delay time set. Since the preset reference delay time matches the actual flight time of the fast neutron, the determination is made as to whether each time difference matches the actual flight time of the fast neutron. If each time difference is determined to be included in the preset reference delay time set, i.e., each time difference matches the actual flight time of the fast neutron, the TAC is used to convert the time difference between the logic signal of the optoelectronic system and each delayed logic signal into a pulse voltage signal. The MCA and data acquisition system then analyze and process the pulse voltage signal to obtain the channel address value corresponding to each time difference.

[0061] Here, each time difference is used to calibrate the time-to-amplitude converter and multichannel analyzer used to measure the fast neutron time-of-flight spectrum. Since each time difference is a fixed value, only one channel address is counted on the obtained pulse amplitude spectrum, and such channel address and time difference have a one-to-one correspondence.

[0062] Step S204 , performing data fitting on each time difference and the channel address value corresponding to each time difference to obtain the relationship between time and channel address, so as to complete the time scale of the fast neutron time-of-flight spectrum.

[0063] Here, each channel address value is the channel address corresponding to each time difference. Based on this, data fitting processing is performed on each time difference and its corresponding channel address value to obtain the relationship between time and channel address, thereby completing the time scale of the fast neutron flight time spectrum.

[0064] In the embodiment of the present application, the time scale of the fast neutron flight time spectrum is implemented through the above-mentioned steps S201 to S204. Based on this, when the fast neutron flight time spectrum is obtained, the relationship between time and channel address can be used to determine the time difference corresponding to the channel address of the pulse amplitude spectrum, that is, the flight time of the fast neutron, and further determine the energy of the fast neutron.

[0065] The present invention provides a method for calibrating a fast neutron time-of-flight spectrum. The method comprises: first obtaining a logic signal of an optoelectronic system and at least two delayed logic signals corresponding to the logic signal of the optoelectronic system, wherein the at least two delayed logic signals are signals obtained by delaying the logic signal of the optoelectronic system; then, using the waveform displayed on an oscilloscope to determine the time difference between the logic signal of the optoelectronic system and each delayed logic signal; then, when each time difference is included in a preset reference delay time set, calibrating a time-amplitude converter and a multi-channel analyzer used for fast neutron time-of-flight spectrum measurement using each time difference to obtain a time pulse amplitude spectrum corresponding to each time difference, and obtaining a channel address value corresponding to each time difference from each time pulse amplitude spectrum; finally, performing data fitting on each time difference and the channel address value corresponding to each time difference to obtain a relationship between time and channel address, thereby completing the time calibration of the fast neutron time-of-flight spectrum. In this way, on the one hand, the signal source uses a luminous body, and the signal source does not require a neutron source to excite a neutron detector to generate an electrical signal, thereby preventing personnel from being harmed by radiation. On the other hand, the oscilloscope can accurately determine the time differences between the logic signal of the optoelectronic system and each delayed logic signal, that is, ensure the accuracy of the time difference between the logic signal of the optoelectronic system and each delayed logic signal. Based on this precise time difference, the precise relationship between time and channel address can be determined, that is, the time scale of the fast neutron flight time spectrum can be accurately completed, and the effectiveness and accuracy of fast neutron energy measurement can also be improved.

[0066] In some embodiments, the above step S203 of "using each time difference to calibrate the time-to-amplitude converter and the multi-channel analyzer used for fast neutron time-of-flight spectrum measurement, obtaining the time pulse amplitude spectrum corresponding to each time difference, and obtaining the channel address value corresponding to each time difference from each time pulse amplitude spectrum" can be implemented by the following steps S2031 and S2032:

[0067] Step S2031 , performing time-amplitude conversion processing on each time difference in turn to obtain a pulse voltage signal corresponding to each time difference.

[0068] Here, TAC can be used to perform time-to-amplitude conversion on each time difference to obtain a pulse voltage signal corresponding to the time difference between the logic signal of the optoelectronic system and each delayed logic signal.

[0069] TAC stands for Time-to-Amplitude Converter, which is an electronic component that can generate an output signal whose amplitude is proportional to the time interval (ie, the time difference) between two input signals.

[0070] In actual implementation, the second logic signal can be delayed in order from small to large time difference; then, the logic signal of the photoelectric system (first logic signal) and the delayed second logic signal are input into the time-to-amplitude converter, and the time difference between the two signals is converted into a pulse voltage signal.

[0071] Step S2032: Measure the pulse voltage signal using a multi-channel analyzer and a data acquisition system to obtain a time pulse amplitude spectrum, and obtain the channel address value corresponding to each time difference from each time pulse amplitude spectrum.

[0072] Here, each pulse voltage signal can be analyzed through MCA, and then combined with the data acquisition system to obtain the time pulse amplitude spectrum, that is, the pulse voltage signal is recorded on the corresponding channel address value according to the amplitude. Since the time difference corresponds to the pulse voltage signal, and the pulse voltage signal corresponds to the channel address value, there is also a corresponding relationship between the time difference and the channel address value, that is, the channel address value corresponding to each time difference is obtained.

[0073] In the embodiment of the present application, through the above-mentioned steps S2031 and S2032, the time-to-amplitude converter and the multi-channel analyzer used for fast neutron time-of-flight spectrum measurement are calibrated using each time difference to obtain the time pulse amplitude spectrum corresponding to each time difference, and the channel address value corresponding to each time difference is obtained from each time pulse amplitude spectrum.

[0074] In some embodiments, when executing the above step S204 of "performing data fitting on each time difference and the track address value corresponding to each time difference to obtain the relationship between time and track address", the following steps S2041 and S2042 can be used to implement the above process:

[0075] Step S2041 , performing data fitting processing on each time difference and the track address value corresponding to each time difference to obtain a fitting function between the time difference and the track address value.

[0076] Here, each time difference and its corresponding track address value may be fitted by a linear fitting method, thereby obtaining a fitting function between the time difference and the track address value.

[0077] Step S2042: Determine the fitting function as the relationship between time and address.

[0078] Here, the fitting function obtained by fitting is the relationship between time and address.

[0079] In the embodiment of the present application, through the above steps S2041 and S2042, the fitting function relationship between the time difference and the track address value can be determined by linear fitting, that is, the relationship between time and track address can be determined.

[0080] In some embodiments, before executing the above step S201 "obtaining the logic signal of the photoelectric system and at least two delayed logic signals corresponding to the logic signal of the photoelectric system", it is necessary to convert, shape and delay the light signal emitted by the signal source to obtain the logic signal of the above photoelectric system and at least two delayed logic signals corresponding to the logic signal of the photoelectric system. In order to avoid the neutron source and its induced radioactive radiation damage in the related technology, in the embodiment of the present application, the light-emitting body of the photoelectric switch can be used as the signal source instead of the traditional neutron detector as the signal source, so as to avoid the occurrence of radiation damage to personnel. Based on this, before executing the above step S201 "obtaining the logic signal of the photoelectric system and at least two delayed logic signals of the logic signal of the photoelectric system", as Figure 3 As shown, the following steps S001 to S003 may also be performed:

[0081] Step S001: Acquire an optical signal emitted by a signal source, perform photoelectric conversion on the optical signal, and obtain a logic signal of the photoelectric system.

[0082] Here, the signal source can emit an optical signal, which is then converted and processed by the optoelectronic conversion circuit to produce an electrical signal, which serves as the logic signal of the optoelectronic system. The optoelectronic conversion circuit converts the optical signal into a corresponding electrical signal based on characteristics such as the intensity of the input optical signal and outputs the converted electrical signal.

[0083] In actual implementation, the signal source may include a light emitting body that emits infrared light with a wavelength of 870 nanometers.

[0084] Step S002: using a three-way module to convert the logic signal of the optoelectronic system into a first logic signal and a second logic signal.

[0085] Here, the three-way module can output two signals that are the same as the input signal. Based on this, the logic system of the optoelectronic system is input into the three-way module, and two signals can be output through the three-way module. These two signals can be recorded as the first logic signal and the second logic signal, wherein the first logic signal and the second logic signal are the same as the logic signal of the optoelectronic system.

[0086] Step S003 : The delay stretcher performs delay processing on the second logic signal according to each reference delay time in a preset reference delay time set, to obtain at least two delayed logic signals.

[0087] Here, the delay module of the delay stretcher can be used to sequentially delay the second logic signal according to each reference delay time in a preset reference delay time set, thereby obtaining a delayed logic signal corresponding to each reference delay time. Specifically, the output signal (the second logic signal) is delayed to obtain at least two delayed logic signals, while the output signal (the first logic signal) is not delayed. Thus, each time the output signal (the second logic signal) is delayed once, a time difference between a delayed logic signal and the output signal (the first logic signal) can be obtained.

[0088] During actual implementation, the number of at least two delayed logic signals is the same as the number of reference delay times.

[0089] In some embodiments, the first logic signal is input into the Start interface of the TAC. Since the first logic signal is the logic signal of the photoelectric system, the logic signal of the photoelectric system is input into the Start interface of the TAC. At the same time, each delayed logic signal is input into the Stop interface of the TAC one by one.

[0090] In an embodiment of the present application, through the above-mentioned steps S001 to S003, the device that emits the optical signal can be used as a signal source, and then the optical signal is converted, shaped, delayed, etc. to obtain the logic signal of the optoelectronic system and at least two delayed logic signals corresponding to the logic signal of the optoelectronic system. In this way, there is no need to find a suitable neutron source, and it can also avoid radiation damage to personnel, while also simplifying the experimental process.

[0091] In some embodiments, in order to prevent personnel from being harmed by radiation, a detector that does not require a radiation source may also be used as a signal source.

[0092] Based on the above embodiments, the present invention further provides a method for calibrating the fast neutron time-of-flight spectrum. The fast neutron time-of-flight spectrum calibration is to calibrate TAC and MCA. The existing takeoff signal generator for thermal neutron time-of-flight measurement in the laboratory is used as the signal source for the fast neutron time-of-flight spectrum calibration. The signal source uses the luminous element of a photoelectric switch, and the circuit that converts infrared light into an electrical signal is as follows: Figure 4 As shown, through Figure 4 The conversion circuit in the optical signal can convert the optical signal into an electrical signal. Then, after the electrical signal passes through the delay stretcher GG8020, the following Figure 5 The signal shown is a logic signal.

[0093] from Figure 5 It can be seen that the signal after the electrical signal passes through GG8020 is a logic signal with an amplitude of -0.8 volts (volt, V) and a time width of 40ns (the signal width is adjustable). The signal after passing through GG8020 is used as the signal source for the fast neutron flight time spectrum scale. A three-way signal is used to split the signal into two and respectively connect to the other two modules of GG8020. Among them, GG8020 has a total of 8 independent modules. Since the factory setting of the jumper of GG8020 is in the delay time range of 70ns to 1000ns, the time scale range demonstrated in the embodiment of this application is 0 to 1000ns, and the delay times used for the scale are 150ns, 300ns, 450ns, 600ns, 750ns, and 900ns. The electronic block diagram used for the measurement is shown in Figure 6. Figure 6 In the figure, the electronics block diagram includes a delay stretcher 601, a time-to-amplitude converter 602, a multi-channel analyzer 603 and a data acquisition system 604.

[0094] When there is no delay in the two signals, the relationship between the two signals is as follows: Figure 7 As shown in the figure, since the zero point of the time spectrum is at the "negative track address", the corresponding time pulse amplitude spectrum is not measured. Based on this, the TAC Stop signal is delayed in various situations.

[0095] In some embodiments, when the signal delay of the Stop interface for TAC is 150ns, the relationship between the two signals is as follows: Figure 8 As shown, the time pulse amplitude spectrum of the TAC Stop signal when it is delayed by 150ns is as follows: Figure 9 As shown by Figure 9 It can be seen that the channel address value corresponding to a delay of 150ns is 147.

[0096] In some embodiments, when the signal delay of the Stop interface for TAC is 300ns, the relationship between the two signals is as follows: Figure 10As shown, the time pulse amplitude spectrum of the TAC Stop signal when it is delayed by 300ns is as follows Figure 11 As shown by Figure 11 It can be seen that the channel address value corresponding to a delay of 300ns is 299.

[0097] In some embodiments, when the signal delay of the Stop interface for TAC is 450ns, the relationship between the two signals is as follows: Figure 12 As shown, the time pulse amplitude spectrum of the TAC Stop signal when it is delayed by 450ns is as follows: Figure 13 As shown by Figure 13 It can be seen that the channel address value corresponding to the delay of 450ns is 451.

[0098] In some embodiments, when the signal delay of the Stop interface for TAC is 600ns, the relationship between the two signals is as follows: Figure 14 As shown, the time pulse amplitude spectrum of the TAC Stop signal when it is delayed by 600ns is as follows: Figure 15 As shown by Figure 15 It can be seen that the channel address value corresponding to a delay of 600ns is 603.

[0099] In some embodiments, when the signal delay of the Stop interface for TAC is 750ns, the relationship between the two signals is as follows: Figure 16 As shown, the time pulse amplitude spectrum of the TAC Stop signal when it is delayed by 750ns is as follows: Figure 17 As shown by Figure 17 It can be seen that the channel address value corresponding to a delay of 750ns is 753.

[0100] In some embodiments, when the signal delay of the Stop interface for TAC is 900ns, the relationship between the two signals is as follows: Figure 18 As shown, the time pulse amplitude spectrum of the TAC Stop signal when it is delayed by 900ns is as follows: Figure 19 As shown by Figure 19 It can be seen that the channel address value corresponding to a delay of 900ns is 903.

[0101] from Figure 9 、 Figure 11 、 Figure 13 、 Figure 15 、 Figure 17 and Figure 19 The pulse amplitude spectrum channel addresses corresponding to the time intervals of 150ns, 300ns, 450ns, 600ns, 750ns, and 900ns are 147, 299, 451, 603, 753, and 903, respectively. The channel addresses correspond to the aforementioned channel address values. The relationship between time and channel address can be expressed in Table 2:

[0102] Table 2 Time and address relationship of TAC and MAC time scale

[0103] Time / ns 150 300 450 600 750 900 Road address 147 299 451 603 753 903

[0104] In some embodiments, the Python computer language can be used to fit the data in Table 2 with a linear function to obtain the relationship between time and address as shown in formula (2).

[0105] Time = 0.9917*address+3.377 (Formula (2))

[0106] In the examples of this application, the fitting results are as follows: Figure 20 shown.

[0107] The fast neutron time-of-flight spectrum calibration method provided in the embodiment of the present application uses a device capable of generating a standard NIM signal as a signal source for the fast neutron time-of-flight spectrum calibration (a detector that does not require a radioactive source can also be used as a signal source through fast playback and a timer). In this way, there is no problem of a radioactive source. The signals connected to the Start interface and the Stop interface of the TAC can be first connected to an oscilloscope to accurately read the time difference between the two signals, thereby avoiding the problem of inaccurate nominal value of the delay device.

[0108] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are for description only and do not represent the advantages and disadvantages of the embodiments.

[0109] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0110] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0111] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed across multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment of the present application.

[0112] In addition, all functional units in the embodiments of the present application can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the above-mentioned integrated units can be implemented in the form of hardware or in the form of hardware plus software functional units.

[0113] Those skilled in the art will understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above-mentioned method embodiments; and the aforementioned storage medium includes: mobile storage devices, ROM, disks or optical disks, and other media that can store program codes.

[0114] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application, or the part that contributes to the relevant technology, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling an AC to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks or optical disks.

[0115] The above is merely an embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A fast neutron time-of-flight spectrum calibration method, characterized in that: The method comprises: Acquire a logic signal of the optoelectronic system and at least two delayed logic signals corresponding to the logic signal of the optoelectronic system, wherein the at least two delayed logic signals are signals obtained by delaying the logic signal of the optoelectronic system; Determining the time difference between the logic signal of the optoelectronic system and each delayed logic signal using an oscilloscope; When each time difference is included in a preset reference delay time set, the time-to-amplitude converter and the multi-channel analyzer used for fast neutron time-of-flight spectrum measurement are calibrated using the time differences to obtain a time pulse amplitude spectrum corresponding to each time difference, and the channel address value corresponding to each time difference is obtained from each time pulse amplitude spectrum; Data fitting is performed on the time differences and the channel address values ​​corresponding to the time differences to obtain the relationship between the time differences and the channel addresses, so as to complete the time scale of the fast neutron time-of-flight spectrum.

2. The method according to claim 1, wherein The method of calibrating a time-to-amplitude converter and a multi-channel analyzer used for fast neutron time-of-flight spectrum measurement using the time differences to obtain time pulse amplitude spectra corresponding to the time differences, and obtaining channel address values ​​corresponding to the time differences from the time pulse amplitude spectra, includes: Performing time-amplitude conversion processing on each of the time differences in turn to obtain a pulse voltage signal corresponding to each time difference; The pulse voltage signal is measured by using a multi-channel analyzer and a data acquisition system to obtain a time pulse amplitude spectrum, and the channel address value corresponding to each time difference is obtained from each time pulse amplitude spectrum.

3. The method according to claim 1, wherein The performing data fitting on the time differences and the track address values ​​corresponding to the time differences to obtain the relationship between the time differences and the track addresses includes: Performing data fitting processing on the time differences and the track address values ​​corresponding to the time differences in a linear fitting manner to obtain a fitting function between the time differences and the track address values; The fitting function is determined as the relationship between the time difference and the track address.

4. The method according to claim 1, wherein The method further comprises: Acquire an optical signal emitted by a signal source, perform photoelectric conversion on the optical signal, and obtain a logic signal of the photoelectric system; Converting the logic signal of the optoelectronic system into a first logic signal and a second logic signal by using a three-way module; The delay stretcher performs delay processing on the second logic signal according to each reference delay time in a preset reference delay time set to obtain the at least two delayed logic signals.

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